DC1901A Analog Devices

DEMO MANUAL DC1901A LTC3639EMSE High Efficiency 150V, 100mA Synchronous Buck Converter DESCRIPTION Demonstration circuit 1901A is a 150V input, 100mA is included to allow multiple boards to be paralleled for output DC/DC power supply featuring the LTC3639. The higher output current. IC operates in a high efficiency Burst Mode operation Output voltage between 800mV and V can be programmed IN and includes internal high and low side power MOSFETs. using optional resistors. (Higher voltage rating output The board will accept an input voltage between 4V and capacitors may be required.) 150V, and provide jumper selected output voltages of The LTC3639 data sheet gives a complete description of the 1.8V, 3.3V, 5V and an option for additional voltages. The IC operation and application information. The data sheet IC includes internal soft-start and a provision for increas- must be read in conjunction with this quick start guide. ing soft-start time. Design files for this circuit board are available at Included on the board is an ON/OFF jumper that can also DEMO MANUAL DC1901A QUICK START PROCEDURE Demonstration circuit 1901A is easy to set up to evaluate 7. With power off, move jumpers JP1 and JP2 to the other the performance of the LTC3639. Refer to Figure 1 for fixed voltage settings (1.8V or 3.3V). Repeat steps 5 the proper measurement equipment setup and follow the and 6. Check for the proper output voltage and other procedure below: parameters. 1. With power off, connect the input power supply (set NOTE: When measuring the output or input voltage ripple, for 0V) to V and GND (input return). do not use the long ground lead on the oscilloscope probe. IN See Figure 2 for the proper scope probe technique. Short, 2. Select 5V output using jumper JP1 (B position) and stiff leads need to be soldered to the (+) and () terminals JP2 (A position). Select ON position for JP3. of an output capacitor. The probes ground ring needs to 3. Connect the 5V output load between V and GND touch the () lead and the probe tip needs to touch the OUT (Initial load: no load). (+) lead. 4. Connect the DVMs to the input and outputs. ADDITIONAL NOTES: 5. Turn on the input power supply and slowly increase to CAUTION: 12V. Check for the proper output voltages. (5V output Be careful when testing with high voltage. High should be within 5V 2%.) voltage can result in an electric shock if care is 6. Once the proper output voltages are established, ad- not taken. just the loads within the operating range and observe For 5V output, V input voltage should be at least 5V or the output voltage regulation, ripple voltage and other IN higher. parameters. Figure 1. Proper Measurement Equipment Setup dc1901af 2